Sound and Vibration Instrument Hire and Calibration

GRAS 40AI and 40AK Specifications

The GRAS 40AI and 40AK have been withdrawn, the following details are for information

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GRAS 40AI   : Sound Intensity Microphones - matched pair

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GRAS 40AK : Sound Intensity Microphones - matched pair with spacers etc.

Open Circuit Sensitivity : 25 mV/Pa at 250 Hz, nominal, see note 1
Frequency Response : 2.5 Hz - 10 kHz ± 1 dB
Dynamic Range - upper limit : 152 dB re 20 µPa, 3% distortion
Dynamic Range - lower limit : 20 dBA re 20 µPa, thermal noise
Polarisation Voltage : 200 V
Cartridge Capacitance : 19.5 pF, polarized, nominal
Resonance Frequency : 12 kHz, 90 ° phase shift
Effective Front Volume : 25 mm³ nominal at 250 Hz
Vibration Sensitivity : 62 dB re 20 µPa, see note 2
Temperature Range : - 10 to + 50 °C
Mean Temperature Coefficient : 0.01 dB / °C
Phase Response, 50 Hz - 250 Hz : < 0.05 °
Phase Response, 250 Hz - 6.3 kHz : < f / 5000 °
Weight : 10 g
Note 1 : The stated sensitivities are the open circuit sensitivities. When used on a GRAS type 26AA preamplifier, the sensitivities are typically 0.2 dB lower
Note 2 : Equivalent SPL for 1 ms^-2 per perpendicular to diaphragm
IEC 1094-4 Type Designation : WS2F
Length with protection grid : 16.2 mm
Diameter with protection grid : 13.2 mm
Diameter without protection grid : 12.7 mm
Thread - protection grid : 12.7 mm, 60 UNS
Thread - preamplifier : 11.7 mm, 60 UNS
E&OE - specifications subject to change without notice.
* Our standard hire charges are based on a 4-day minimum period, details other options.